Submitted to: Functional and Integrative Genomics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/17/2002
Publication Date: 8/14/2002
Citation: Interpretive Summary: The high-molecular-weight (HMW) glutenins are critical proteins for wheat quality. These proteins confer the visco-elastic character to wheat doughs that allows the wide range of food products to be produced from wheat. Although significant research efforts have gone into the study of these proteins and their genes, no detailed information has been available on the region of the wheat genome containing the HMW-glutenin genes. This information is important to fully understand the control of these genes, to determine what other genes are in the immediate vicinity, and to give a clearer basis for the study of these genes and proteins. This study reports the organization of the wheat genome including and surrounding the two HMW-glutenin genes from the D-genome of wheat - the two genes most signficantly correlated to wheat quality.
Technical Abstract: A bacterial-artificial-chromosome (BAC) clone from the genome of Triticum tauschii, the D-genome ancestor of hexaploid bread wheat, was sequenced and the presence of the two paralogous x- and y- type high-molecular-weight (HMW) glutenin genes of the Glu-D1 locus was confirmed. These two genes occur in the same orientation, are 51,489 bp apart, and the separating DNA includes a 31,000 bp cluster of retrotransposons. A second retrotransposon cluster of 32,000 bp follows the x-type HMW-glutenin gene region. Each HMW-glutenin gene is found within a region of mainly unique DNA sequence which includes multiple additional genes including an active endosperm globulin gene not previously reported in the Triticeae family, a leucine-rich-repeat (LRR) type gene truncated at the 5' end of the BAC, a kinase gene of unknown activity, remnants of a paralogous second globulin gene, and genes similar to two hypothetical rice genes. The newly identified globulin genes are assigned to a locus designated Glo-2. Comparison to available orthologous regions of the wheat A and B genomes show rapid sequence divergences flanking the HMW-glutenin genes, and the absence of two hypothetical and unknown genes found 5' to the B-genome x-type ortholog. The region surrounding the Glu-D1 locus is similar to other reported Triticeae BAC sequences; i.e., small gene islands separated by retrotransposon clusters.